Supplementary Code: Natural Selection on Reproductive Timing Varies by Education in 20th-century Estonia

This dataset contains individual-level reproductive and socioeconomic information for Estonian citizens born between 1925 and 1977 who survived to at least age fifteen. For every person the file lists sex, year of birth, total number of children born up to 2022, and the birth years of the first and last child. Self-reported educational attainment is available for the majority of individuals and is recorded in five categories ranging from primary to tertiary education. Analysis of these records shows that women with only primary education consistently realised the largest completed family sizes across the entire birth-year range examined. Among men a positive association between education and reproductive success emerged in cohorts born after the early 1950s, so that tertiary-educated men eventually out-reproduced their less-educated peers despite delaying parenthood. Educational differences in the timing of reproductive events were also pronounced. Women with primary education both entered parenthood earliest and experienced the strongest directional selection favouring an early first birth, whereas the same education group in men displayed the shortest interpregnancy intervals and the fastest overall reproductive tempo. Stabilising selection on intermediate interbirth intervals was strongest among parents with minimal schooling, yet these men and women were likewise subject to selection favouring a late cessation of reproduction. Despite that pressure, fathers with primary education were generally the first to terminate childbearing. Taken together, the dataset demonstrates that selection on reproductive timing has been consistently stronger in the lowest educational strata and that temporal trends in reproductive schedules do not simply mirror the selective forces acting on recent generations. The files therefore offer a resource for investigating how social stratification intersects with natural selection in a contemporary human population.本数据集收录了1925年至1977年间出生、且至少存活至15岁的爱沙尼亚公民的个体层面生育与社会经济信息。该文件为每位个体记录了性别、出生年份、截至2022年的总生育子女数，以及首胎与末胎的出生年份。多数个体提供了自我报告的受教育程度，该信息被划分为从初等教育到高等教育共五个等级。 对这些记录的分析显示，仅接受初等教育的女性在所有考察的出生队列中，始终拥有最大的终身生育规模。对于男性而言，在1950年代初之后出生的队列中，教育水平与生育成功率呈现正相关关系：尽管推迟生育，接受高等教育的男性最终的生育子女数仍多于受教育程度较低的同辈。 生育时机的教育差异同样显著。仅接受初等教育的女性不仅最早进入生育阶段，且受到最强的定向选择，倾向于早育首胎；而男性中的同等教育群体则拥有最短的妊娠间隔，整体生育节奏最快。在受教育程度最低的父母群体中，针对中等生育间隔的稳定选择效应最强，但这些男性和女性同样受到选择压力，倾向于较晚停止生育。尽管存在这一选择压力，仅接受初等教育的父亲通常是最早停止生育的群体。 综合来看，本数据集表明，针对生育时机的选择在教育程度最低的阶层中始终更强，且生育时序的时间趋势并非简单反映作用于当代人群的选择压力。因此，该数据集为探究社会分层如何与当代人类群体的自然选择相互作用提供了研究资源。